Unlike standard interconnect services provided by today's cellular systems, a dispatch group call service enables a user to communicate with a group of people simultaneously and instantaneously, usually by depressing a push-to-talk (PTT) button. Using a cellular communication system's standard interconnect services would not allow such a call to occur instantaneously since either a telephone number would need to be dialed for a three-way call or arrangements would need to be made to setup a conference call.
Likewise, the dispatch service enables a user to communicate with another user quickly and spontaneously. This feature is ideal for two people who are working together but are unable to speak with one another directly such as two people working in concert but in different parts of a building. Where a wireless telephone call is more appropriate for a conversation, short messages between two people as they work are better facilitated by the dispatch call service.
During a typical dispatch call, over-the-air channels assigned to the call are maintained until an inactivity timer (hang timer) has expired. In particular, a base station monitors the dispatch call, and if there exists no activity for a period of time, the base station, in collaboration with other infrastructure elements, will drop the over-the-air channels broadcasting the call to the remote units. If activity resumes, the base station will then reassign channels to the conversation, and again monitor for inactivity.
One feature provided to dispatch call participants is the ability to opt-out of a dispatch call. For example, a particular user may be a member of a group, yet have no interest in participating in a particular group call (e.g., the user is in a meeting, Church, . . . , etc. and does not want to be bothered). In this situation, the user may instruct the communication system that it does not wish to participate in the call. The communication system will then drop the channel providing the call to the remote unit and the user will no longer participate in the particular group call. During subsequent group calls (at later times), the user will again be pulled into the call.
Although the above procedure allows a user to leave a particular call and remain a participant in subsequent calls, a problem can arise when the hang timer is allowed to expire and the current call continues after such. In such situations, a different call is set up having the original participants. A user that has chosen to leave the original group call will again be pulled into the call, and must again chose to leave the call. Therefore, a need exists for a method and apparatus for providing a dispatch call within a communication system that reduces the chances that a user will be pulled back into a call that they have chosen to leave.